Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Accumulated other comprehensive income (loss) [Line Items]
Balance at January 1		$ 2,399
Amortization of interest rate contracts reclassified from comprehensive income to interest expense	[1]	1,191	$ 1,230	$ 1,104
Balance at December 31,		5,029	2,399
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Schedule of Accumulated other comprehensive income (loss) [Line Items]
Balance at January 1		2,056
Amortization of interest rate contracts reclassified from comprehensive income to interest expense	[2]	1,191	1,230	1,104
Balance at December 31,		4,725	2,056
Accumulated Other Comprehensive Income (Loss) [Member]
Schedule of Accumulated other comprehensive income (loss) [Line Items]
Balance at January 1		2,399	(1,745)	(5,192)
Change in fair market value during year		1,478	2,948	2,371
Allocation of unrealized (gains)/losses on derivative financial instruments to noncontrolling interests		(39)	(34)	(28)
Amortization of interest rate contracts reclassified from comprehensive income to interest expense		1,191	1,230	1,104
Balance at December 31,		5,029	2,399	(1,745)
Accumulated Other Comprehensive Income (Loss) [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Schedule of Accumulated other comprehensive income (loss) [Line Items]
Balance at January 1		2,056	(2,122)	(5,597)
Change in fair market value during year		1,478	2,948	2,371
Amortization of interest rate contracts reclassified from comprehensive income to interest expense		1,191	1,230	1,104
Balance at December 31,		$ 4,725	$ 2,056	$ (2,122)

[1] Amounts reclassified from comprehensive income to interest expense within the Consolidated Statements of Operations.

[2] Amounts reclassified from comprehensive income to interest expense within the Consolidated Statement of Operations.